This invention relates to electro ceramic components such MEMS arrays and methods for fabricating electro ceramic components with high density interconnects and that maintain relative internal alignment. Components constructed according to the invention are MEMS arrays or other micromachined elements.
Conventional MEMS array structures comprise Silicon on Insulator (SOI) array structures in which is fabricated an integrated electrode array. One of the problems encountered is placement accuracy control from within the substrate element to the bottom surface of the electrostatic actuation electrodes due to fabrication tolerance limitations. In particular, when the substrate is a low-temperature co-fired ceramic (LTCC), shrinkage variance of the ceramic may be greater than is allowable for a particular design. What is needed is a solution that allows for achievable via alignment accuracy to the underlying actuation electrodes in such manner as to not compromise the device design of the corresponding MEMS actuatable element.
According to the invention, an array apparatus has a micromachined SOI structure, such as a MEMS array, mounted directly on a class of substrate, such as low temperature co-fired ceramic, in which is embedded electrostatic actuation electrodes disposed in substantial alignment with the individual MEMS elements, where the electrostatic electrodes are configured for substantial fanout and the electrodes are oversized such that in combination with the ceramic assembly are configured to allow for placement of the vias within a tolerance of position relative to electrodes such that contact is not lost therebetween at the time of manufacturing.
In a specific embodiment, the electrodes are sized to accommodate the entire space available between MEMS devices even though the required design of the electrodes for the MEMS device may be smaller. This allows for greater tolerance or variance in the placement of vias from the substrate to the actuation electrodes. This structural design allows for an increased density and increased overall array size that is manufacturable. A single or multiple deposition of dielectric material is deposited over the electrodes in the peripheral areas away from the SOI cavities so that the conductive SOI handle is insulated from the electrodes.
The invention will be better understood by reference to the following detailed description in connection with the accompanying illustrations.